Electroactive polymers for lithography

ABSTRACT

Systems and methods for lithography include actuating an electroactive polymer member to position mask and/or substrate.

RELATED APPLICATIONS

For purposes of the USPTO extra-statutory requirements, the presentapplication constitutes a continuation-in-part of U.S. patentapplication Ser. No. 11/132,736, entitled Electroactive Polymers forLithography, naming Roderick A. Hyde and Nathan P. Myhrvold asinventors, filed May 19, 2005 now U.S. Pat. No. 7,473,499, is anapplication of which a currently co-pending application is entitled tothe benefit of the filing date.

The United States Patent Office (USPTO) has published a notice to theeffect that the USPTO's computer programs require that patent applicantsreference both a serial number and indicate whether an application is acontinuation or continuation-in-part. Stephen G. Kunin, Benefit ofPrior-Filed Application, USPTO Official Gazette Mar. 18, 2003, availableat http://www.uspto.gov/web/offices/com/sol/og/2003/week11/patbene.htm.The present Applicant Entity (hereinafter “Applicant”) has providedabove a specific reference to the application(s)from which priority isbeing claimed as recited by statute. Applicant understands that thestatute is unambiguous in its specific reference language and does notrequire either a serial number or any characterization, such as“continuation” or “continuation-in-part,” for claiming priority to U.S.patent applications. Notwithstanding the foregoing, Applicantunderstands that the USPTO's computer programs have certain data entryrequirements, and hence Applicant is designating the present applicationas a continuation-in-part of its parent applications as set forth above,but expressly points out that such designations are not to be construedin any way as any type of commentary and/or admission as to whether ornot the present application contains any new matter in addition to thematter of its parent application(s).

All subject matter of the Related Applications and of any and allparent, grandparent, great-grandparent, etc. applications of the RelatedApplications is incorporated herein by reference to the extent suchsubject matter is not inconsistent herewith.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is related to and claims the benefit of theearliest available effective filing date(s) from the following listedapplications (the “Related Applications”) (e.g., claims earliestavailable priority dates for other than provisional patent applicationsor claims benefits under 35 USC § 119(e) for provisional patentapplications, for any and all parent, grandparent, great-grandparent,etc. applications of the Related Application(s)).

BACKGROUND

Currently, lithography is the most complicated and expensive process inmainstream microelectronic fabrication. As required chip feature sizesgrow ever smaller, lithography techniques are continually updated toachieve the desired resolution. A significant component of the cost oflithography is the cost of manufacture of lithography masks. For certaintypes of lithography, greater resolution may be achievable using contactmethods, in which a mask is placed in contact with a substrate, butthese techniques may also risk damage to the mask and/or the substrate.Proximity printing techniques may avoid damage due to contact betweenthe mask and the substrate, but may require fine control over the exactoffset distance between the mask and substrate. Projection lithographysystems keep the mask relatively remote from the substrate, but may belimited in resolution due to limitations in depth of field for highnumerical aperture optics.

SUMMARY

In one aspect, a lithography apparatus comprises a mask holder having amask location, a substrate holder having a substrate location, and apositioner that shifts the relative positions of the mask holder and thesubstrate holder from a first arrangement to a second arrangement, wherethe second arrangement has a selected relationship between the masklocation and the substrate location. The positioner includes anelectroactive polymer member that shifts the relative positions from thefirst arrangement to the second arrangement.

The apparatus may also include an electrode in electrical communicationwith the electroactive polymer member. Application of a voltage to theelectrode actuates the electroactive polymer member. Alternatively, theelectroactive polymer member may be actuated by application of amagnetic field.

In the second arrangement, the mask position may be offset from thesubstrate position by substantially uniform offset distance, forexample, a distance of about 5 μm to about 100 μm, about 1 μm to about 5μm, less than about 1 μm, less than about 100 nm, or less than about 10nm.

The apparatus may also include a distance sensor that monitors relativepositioning of the mask position and the substrate position, and acontroller that controls the shifting of the positioner in response tothe distance sensor. The distance sensor may monitor the distancebetween the mask position in the substrate position at a plurality oflocations. The positioner may include a plurality of active regions, andthe controller may separately control the shifting of each activeregion, for example in response to the monitored distance between themask position and the substrate position at the plurality of locations.The distance sensor may monitor the relative positioning of the maskposition and the substrate position, for example by measuring acapacitance, by measuring an inductance, by optical measurement, byusing an atomic force measurement, or by using evanescent wave coupling.

In the second arrangement, a mask in the mask position and a substratein the substrate position may be in contact. The apparatus may include aforce sensor that monitors a contact force between the mask and thesubstrate, and may also include a controller that controls the shiftingof the positioner in response to the monitored contact force. The forcesensor may monitor contact forces at a plurality of locations. Thepositioner may include a plurality of active regions, and the controllermay separately control the shifting of each active region, for examplein response to the monitored contact force.

The apparatus may also include a stage that brings the mask position andthe substrate position into the first arrangement. The positioner mayshift the relative positions of the mask holder and the substrate holderby moving the mask holder, or it may shift the relative positions a maskholder and the substrate holder by moving the substrate holder. Ineither case, the apparatus may include a spacer interposed between thepositioner and the mask holder or the substrate holder.

The positioner may acts to flatten a mask in the mask position or asubstrate in the substrate position. For example, the positioner maycomprise a plurality of active regions, and each active region may beseparately actuated to shift an adjacent portion of the mask or thesubstrate.

The lithographic apparatus may also comprise an energy source positionedto direct an energy flux through the mask position to the substrateposition. The energy flux may be, for example, electromagneticradiation, an electron beam, an ion beam, or an x-ray beam. Theapparatus may also include a beam directing elements, for example alens, a mirror, or an electromagnetic field generator. The apparatus mayalso comprise a mask that emits light in the mask location. For example,the mask may include a light emitting diode or may fluoresce.

The apparatus may include a mask in the mask location and a substrate inthe substrate location, where the mask has a physical effect on asurface of the substrate when the mask and the surface of the substrateare brought into contact. The chemical composition of the surface may bechanged by contact with the mask, for example by transferring afunctional group from the mask to the substrate, or from the substrateto the mask. The substrate may include a surface coating of a resistcomposition, and the physical effect may be a chemical change in theresist composition.

The electroactive polymer member may include a material selected fromthe group consisting of ferroelectric polymers, dielectric polymers,electrostrictive polymers, electroviscoelastic polymers, liquidcrystals, ionic polymers, carbon nanotubes, electrorheological polymers,and magnetoreological polymers, and it may be an elastomer.

In another aspect, a mask moving system includes a mask holder and anelectroactive polymer member, coupled for force transfer to the maskholder. It may also include a controller that controls a degree ofactuation of the electroactive polymer member, and/or an electrode inelectrical communication with the electroactive polymer member, whereapplication of a voltage to the electrode actuates the electroactivepolymer member. The electroactive polymer member may also be actuated byapplication of a magnetic field.

The system may also include a position monitor coupled to detect theposition of the mask holder relative to a substrate, for example bydetecting a contact force and/or a distance, at one or more locations.Distance may be monitored optically, capacitively, inductively, using anatomic force measurement, or by evanescent wave coupling. The system mayalso include a controller that controls a degree of actuation of theelectroactive polymer member in response to the detected position.

The electroactive polymer member of the mask moving system may comprisea plurality of separately actuatable regions. The system may furthercomprise a controller that independently actuates each member of theplurality of separately actuatable regions. The separately actuatableregions may be arranged so that actuating a subset of them deforms amask in the mask holder. The system may also include a position monitorcoupled to detect the position of the mask holder relative to asubstrate at one or more positions, for example by monitoring contactforce or distance, and the detected position of the mask holder may beused to control the degree of actuation of the electroactive polymermember. Distance may be monitored, for example, optically, capacitively,inductively, by atomic force measurement, or by evanescent wavecoupling. The controller may be responsive to the position monitor.

In another aspect a lithographic apparatus comprises an illuminationsystem and a positioning apparatus including an electroactivepolymer-based movement mechanism. The illumination system is oriented toprovide activating energy to an illumination site. The apparatus mayalso include an object holder configured to position an object inproximity to the illumination site, and/or a substrate supportconfigured to hold a substrate substantially at the illumination site.The positioning apparatus may be configured to provide relative movementof the illumination site and the object, or to move the illuminationsite. The electroactive polymer-based movement mechanism may be coupledto the object holder. The activating energy may be, for example,electromagnetic radiation, an electron beam, an ion beam, or an x-raybeam. The apparatus may also include a beam directing element thatdirects the activating energy, such as a lens, a mirror, or anelectromagnetic field generator. The illumination means may provideactivating energy to the illumination site in a spatial pattern.

In another aspect, a controller for lithographic system comprises areceiver that receives a distance measurement signal, a processor thatuses the distance measurement signal to determine an actuation profilefor an electroactive polymer member, and an output that actuates theelectroactive polymer member according to the actuation profile. Thedistance measurement signal may be produced by measuring a distancebetween a mask in a substrate and/or may comprise a plurality ofdistance measurements. The actuation profile may comprise a singledegree of actuation or a plurality of actuation signals. In the lattercase, each actuation signal may be directed to an active region of theelectroactive polymer member. The electroactive polymer member may bepositioned to shift a first surface relative to a second surface, andthe actuation profile may be selected to bring the first surface to apredetermined distance from the second surface, or the actuation profilemay be selected to conform the first surface to the second surface.

In another aspect, a controller for a lithographic system comprises areceiver that receives a force measurement signal, a processor that usesthe force measurement signal to determine an actuation profile for anelectroactive polymer member, and an output that actuates theelectroactive polymer member according to the actuation profile. Theforce measurement signal may be produced by measuring a force between amask in a substrate, and/or may comprise a plurality of forcemeasurements. The actuation profile may comprise a single degree ofactuation or a plurality of actuation signals. In the latter case eachactuation signal may be directed to an active region of theelectroactive polymer member. The electroactive polymer member may bepositioned to shift a first surface relative to a second surface, andthe actuation profile may be selected to bring the first surface intocontact with the second surface at a predetermined contact force, or theactuation profile may be selected to conform the first surface to thesecond surface.

In another aspect to a lithographic method comprises positioning a maskproximate to the substrate in shifting the relative positions of themask and the substrate by actuating electroactive polymer member. Themethod may also include monitoring a distance between the mask and thesubstrate, at one or at a plurality of locations. The electroactivepolymer member may comprise a plurality of separately actuatable activeregions and actuating the electroactive polymer member may includeseparately actuated a subset of the separately actuatable active regionsin response to the monitored distance or distances. The method mayinclude maintaining a selected distance between the mask and thesubstrate (e.g., in the range of about 5 μm to about 100 μm, in therange of about 10 μm to about 50 μm, in the range of about 1 μm to about5 μm, less than about 1 μm, less than about 100 nm, or less than about10 nm) by using the monitored distance as a feedback signal to adjust adegree of actuation of the electroactive polymer member.

Shifting the relative position of the mask and the substrate may includebringing the mask and the substrate into contact and further may includemonitoring a contact force between them, at one or at a plurality oflocations. The monitored contact force may be used as a feedback signalto adjust a degree of actuation of the electroactive polymer member. Theelectroactive polymer member may comprise a plurality of separatelyactuatable active regions, a subset of which may be separately actuatedin response to the monitored contact forces. Positioning the maskproximate to the substrate may include moving the mask or the substratewith a stage.

Changing the position or shape of the electroactive polymer member mayflatten the substrate or mask. The method may also include measuringflatness of the substrate or mask. The electroactive polymer member maycomprise a plurality of separately actuatable active regions, a subsetof which may be separately actuated in response to the measured flatnessof the substrate or mask. The substrate or mask flatness measurement maybe done prior to or concurrently with actuating the electroactivepolymer member.

The method may also include exposing the substrate to an energy fluxthrough the mask. For example, the energy flux may be electromagneticradiation, an electron beam, an ion beam, or an x-ray beam. Thesubstrate may be coated with a resist composition and the energy fluxmay cause a chemical change in the resist composition. The method mayfurther comprise removing either resist composition exposed to theenergy flux or resist composition not exposed to the energy flux.

The method may also include exposing the substrate to an energy fluxfrom the mask. For example, a voltage may be applied to the mask, eitherwhile it is in contact with the substrate or while it is offset from thesubstrate. Alternatively, the mask may emit light. For example, the maskmay include a light-emitting diode, or at least a portion of the maskmay fluoresce.

The method may also include causing a physical effect on the surface ofthe substrate by contact with the mask. The physical effect may bechanging the chemical composition of the surface, for example bytransferring a functional group from the mask to the substrate or fromthe substrate to the mask. The substrate may include a surface coatingof a resist composition and the physical effect may be a chemical changein the resist composition.

The electroactive polymer member may comprise a material selected fromthe group consisting of ferroelectric polymers, dielectric polymers,electrostrictive polymers, electroviscoelastic polymers, liquidcrystals, ionic polymers, carbon nanotubes, electrorheological polymers,and magnetorheological polymers, and/or it may include an elastomer.

In another aspect, a method of positioning a mask comprises applying aforce with an electroactive polymer. Applying a force may includeapplying a force to a mask moving mechanism, which may include a maskholder. The method may also include positioning a mask in a firstlocation in a lithographic system, and may further include moving themask from the first location to an imaging location. The motion from thefirst location to the imaging location that may be responsive toapplying the force with the electroactive polymer. Applying a force mayinclude the forming the mask, for example by flattening it or byconforming it to a substrate.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows schematically a lithography system.

FIG. 2 shows schematically another lithography system.

FIG. 3 shows a flow chart illustrating operation of a lithographicmethod.

DETAILED DESCRIPTION

Electroactive polymers respond to electrical or magnetic stimulation bychanging or tending to change shape. Polymers may use a wide variety ofmechanisms to achieve this behavior, including but not limited toferroelectric polymers, dielectric polymers, electrostrictive polymers,electroviscoelastic polymers, liquid crystals, ionic polymers, carbonnanotubes, electrorheological polymers, and magnetorheological polymers.Many such polymers may exhibit desirable features such as high actuationstrains, mechanical resilience, and good response times.

Either the mask, the substrate, or both may be positioned in alithographic system with an electroactive polymer. Particularly in acontact lithography system, it may be desirable to use a relativelyresilient polymer (e.g., a polymer that is partially or fullyelastomeric). This may minimize contact forces and resulting damage toeither the mask or the substrate. A resilient polymer may also helpconform the mask to the substrate (or vice versa).

Electroactive polymers can provide a fine degree of control of positionof the mask and/or the substrate. Their relatively high actuationstrains and fast response times can allow precise positioning, whiletheir resilience can provide a more robust system. A fine degree ofcontrol and the ability to monitor and correct flatness of the substrateand/or the mask may be helpful in projection lithography systems, and toprovide adequate focus in systems having optical systems with limitednumerical apertures. Fine control may also be applicable in proximityprinting systems, where a small offset can enhance resolution at a riskof damage to mask and/or substrate, if they are allowed to contact.Electroactive polymers may also be adapted operate as part offorce-feedback systems, which may be applicable in contact lithography.Their resilience may also help minimize damage due to contact in bothproximity and contact lithography systems.

FIG. 1 shows schematically one embodiment of a lithography system.Illumination source 100 may be a light source (optical lithography), anx-ray source, an electron or ion beam source, or any other source of anenergy flux that can be used for lithography. Illumination may becontinuous, burst, or intermittent, as is typically defined byconfigurations and parameters of the lithography system. In theillustrated system, light is focused by lens 102. While the embodimentof FIG. 1 incorporates the lens 102, any other beam-directing, shaping,splitting, filtering, or polarizing element or combination of elements,or any other optically interactive elements may direct, process, shapeor otherwise interact with an energy flux to provide illuminationappropriate for the system. Such elements may include mirrors,electromagnetic fields (which may be static or dynamic), diffractiveelements, refractive elements, lenses, or any other optical elementsappropriate for the configuration. “Optical element” or “beam-directingelement,” as used herein, is intended to include all elements suitablefor changing the direction, focus, polarization, or other properties ofthe illumination energy flux, which may be, but need not be,electromagnetic energy of any type (e.g., “optical elements” in thiscontext include electromagnetic fields that may be used to directelectron or ion beams). Morever, in some applications, the illuminationmay be used direct from the source 100 without any beam-directingelements. Also, although the lens 102 is represented by a symboltypically associated with a refractive lens, other types of lenses maybe incorporated, including Fresnel lenses, diffractive lenses, or othertypes of lenses or combinations of lenses. Further, although therepresentation of FIG. 1 shows an optical element, represented by lens102, between the light source 100 and the mask, beam-directing orhandling elements may also optionally be positioned after mask 104, orelsewhere in the lithography system.

In the illustrated system, after light has been focused by lens 102, itpasses through apertures 106 in mask 104, which is held in place by maskholder 108. Light that passes through the apertures 106 impinges onsubstrate 110, replicating the pattern of the mask. The distance betweenmask 104 and substrate 110 has been greatly increased in FIG. 1 forclarity; though close proximity of mask and substrate generally promotesresolution and may be appropriate in many lithography systems. Inproximity photolithography systems, distances between mask and substrateare currently often in the range of about 5 μm to about 100 μm, or ofabout 10 μm to about 50 μm, but shorter or longer offsets are alsocontemplated, including effectively zero distances in the case ofcontact lithography. In particular, since diffraction effects inproximity systems are minimized when offsets are small, it iscontemplated that distances between mask and substrate may be as low asabout 1 μm, 100 nm, or even 10 nm. Projection printers, on the otherhand, that may hold mask and wafer at arbitrarily large distances fromone another, and typically include optical elements between the mask andthe wafer, may also be used with electroactive polymer members asdescribed below.

As shown in FIG. 1, substrate holder 112 holds substrate 110 inposition, while electroactive polymer member 114 is in direct contactwith the back of the substrate 110. Optionally, a spacer (not shown) maybe interposed between the electroactive polymer member 114 and thesubstrate 110, or the electroactive polymer member may be in contactwith the substrate holder, rather than the substrate. Electrodes 116apply a voltage to the electroactive polymer to actuate it, causing itto lift or lower the substrate 110, for example to place the substrate110 in an image plane of the imaging system. In the embodiment shown inFIG. 1, the electroactive polymer member 114 comprises multiple activeregions 118, which can be separately actuated by separately addressableelectrodes, though in some configurations a single polymer member orpairs of polymer members may be appropriate. These active regions 118allow the substrate to be lifted or lowered at selected points, forexample to flatten it, or to avoid placing pressure on particularlysensitive areas of an inhomogeneous substrate.

An optional distance sensor 120 is illustrated schematically in FIG. 1.Other embodiments may include plurality of distance sensors, or a singlesensor that monitors the distance between the mask 104 and substrate 110at a plurality of locations. If present, sensor 120 may be coupled tooptional controller 122, which may provide a feedback signal toelectroactive polymer member 114. In such embodiments, the feedbacksignal may be used to adjust the actuation of electroactive polymermember 114. For example, the feedback signal may be used to shift thesubstrate to a desired imaging location, or to apply differentactuations to different active regions 118, for example to flatten thesubstrate or to conform it to the mask.

Distance sensors may use any appropriate technology, such as but notlimited to capacitive distance monitoring, inductive distancemonitoring, or optical distance monitoring (which includes monitoring inany electromagnetic frequency range, including X-ray monitoring). Insome embodiments, including but not limited to those having distancesbetween mask and substrate in the range of about 10 nm to about 100 nm,distance measurement may be achieved by interaction of evanescent wavesfrom one surface with the opposing surface (e.g., “plasmon tomography”).In other embodiments, atomic force measurement may be used to monitordistance between mask and substrate. In some embodiments, a singlesensor measures distance between mask and substrate either at a singlepoint or as an average over some or all of the mask/substrate overlaparea. In other embodiments, one or more sensors monitor the distance attwo or more points. In some applications a larger number of sensors,that may be greater than 1,000, may be appropriate.

Another embodiment is illustrated in FIG. 2. In this embodiment, theelectroactive polymer member 114 is positioned above the mask 104, andis arranged to shift the mask, for example into a desired imaginglocation. The member could also be placed below the mask, between it andthe substrate. In either case, a spacer (not shown) may optionally beplaced between the mask 104 and the electroactive polymer member 114,and/or the member 114 may act to shift the mask holder 108, rather thanthe mask directly. Although not shown in FIG. 2, the distance sensor 120and/or the controller 122 of FIG. 1 may also be employed in theconfiguration of FIG. 2. As was shown in FIG. 1, the electroactivepolymer member may comprise active regions 118 which are separatelyactuable. In the embodiment shown, at least a portion of theelectroactive polymer member 114 is at least partially transparent tothe illumination, so that illuminating energy passes through the member114 to reach the mask 104 and eventually the substrate 110. Thistransparency may be a function of the polymer and illumination source100 selected, or may be achieved by other means, such as apertures inthe member 114 or the use of a composite member 114 having regions of atransparent or translucent material.

In other embodiments (which may, but are not required to, use any of theabove-described configurations of mask, substrate, and electroactivepolymer member), the illumination source may be incorporated in,integral to, or carried by the electroactive polymer member 114 or themask 104 itself. For example, the mask may include as an integralportion or a discrete portion, a patterned light emitter, such as anLED-based emitter, or fluorescent regions that can be stimulated to emitphotons. For example, in one embodiment, the mask may be stimulated bylight of a frequency to which a photoresist on the substrate isinsensitive. Patterned fluorescent regions in the mask may then emitlight that exposes the photoresist.

Similarly, the electroactive polymer member 114 may include alight-emitting layer, either at the surface or internally, that producesthe light that passes through mask 104. The electroactive polymer member114 or the mask 104 may also supply a non-optical energy flux to thesubstrate, for example by applying a voltage to the mask that affectsthe adjacent substrate.

In still other embodiments, no illumination system is used. Such “softlithography” systems are described, for example, in Xia and Whitesides,“Soft Lithography,” Annu. Rev. Mater. Sci. 1998, 28:153-184, which isincorporated by reference herein for all that it teaches and suggests.In these approaches, mask 104 is typically used as a stamp or mold toalter the chemistry or form of the substrate in the areas in which itcontacts the substrate. In some of these embodiments, a resilient (e.g.,elastomeric) electroactive polymer member can to allow the mask 104 toconform to the substrate 110. In other embodiments, a relatively stiffelectroactive polymer may be used, and the mask may be conformed to asubstrate that is not perfectly flat by actuating different regions ofthe electroactive polymer member to different degrees, as discussedabove.

Either single-point or multiple-point sensors may be combined with theelectroactive polymer members having multiple active regions, discussedabove. The sensor(s) may detect any variations from a desired shape(e.g., warping) for the mask and/or the substrate, which theelectroactive polymer member can then compensate for by applyingdifferent levels of actuation to different active regions. Distancemeasurements may be relative (e.g., measuring the distance between themask and the substrate), or absolute (e.g., measuring the flatness ofthe mask and/or the substrate).

Lithography systems, particularly (but not only) contact lithographysystems and soft lithography systems, may also use one or more forcesensors to monitor a relationship between the mask and the substrate.Such sensors may provide feedback to guide actuation of theelectroactive polymer, for example to avoid damage to the substrateand/or the mask caused by excessive pressure. In embodiments includingan electroactive polymer member having multiple active regions, thefeedback signal can be used to selectively adjust pressure in differentactive regions.

In some embodiments, it may be useful to employ both distance and forcesensors. For example, in some lithography systems, the mask may “sag”and contact the substrate in some regions, but not others. In suchcases, force sensors may be desirable to monitor areas with contact,while distance sensors monitor areas without contact. A mask and/orsubstrate may also include raised structures outside the main area thatact as guides to alignment. In such embodiments, it may be desirable toemploy force sensor in the area of the raised structure, and a distancesensor in the main area.

FIG. 3 is a flow chart illustrating a lithographic method. As shown, thefirst step 200 is to approximately align the mask and the substrate, forexample by moving one or both with a motorized stage. Next, anelectroactive polymer member is actuated 202 to shift the mask and/orthe substrate towards an imaging position. In one approach, theelectroactive polymer is actuated by applying a voltage under control ofan electronic system controller containing appropriate computerinstructions. Optionally, the distance between the mask and thesubstrate 204 and/or the force between the mask and the substrate 206may be monitored as described previously. The sensors output a signalthat is provided to the electronic system controller as a feedbacksignal. In response, the electronic system controller adjusts theactuation of the electroactive polymer member to bring the mask and/orthe substrate into the imaging position. Once the mask and substrate arepositioned, a resist on the substrate may be exposed 208. This step mayinclude, for example, exposing a photoresist to electromagneticradiation, exposing an electrical resist to an electron or otherparticle beam, or chemically altering a resist by contact with the maskin a soft lithography system. Finally, the exposed resist is typicallydeveloped 210, in either a negative resist process (which removesunexposed resist), or a positive resist process (which removes exposedresist). The latter two steps may not be necessary in all systems, forexample in an electron-beam etch system where the electron beamphysically etches the substrate without need for a resist step. Softlithography systems will often (but not always) omit the developing step210.

The foregoing detailed description has set forth various embodiments,some of which incorporate logic and/or circuits, via the use of blockdiagrams, flow diagrams, operation diagrams, flowcharts, illustrations,and/or examples. Insofar as such block diagrams, operation diagrams,flowcharts, illustrations, and/or examples contain one or morefunctions, operations, or data structures to be performed, manipulated,or stored by logic and/or circuits, it will be understood by thosewithin the art that each such logic and/or circuit can be embodied,individually and/or collectively, by a wide range of hardware, software,firmware, or virtually any combination thereof. For example, someembodiments of the subject matter described herein may be implementedvia Application Specific Integrated Circuits (ASICs), Field ProgrammableGate Arrays (FPGAs), digital signal processors (DSPs), or otherintegrated formats. However, those skilled in the art will recognizethat other embodiments disclosed herein can be equivalently implementedin whole or in part in standard integrated circuits, as one or morecomputer programs running on one or more computers (e.g., as one or moreprograms running on one or more computer systems), as one or moreprograms running on one or more processors (e.g., as one or moreprograms running on one or more microprocessors), as firmware, as analogcircuitry, or as virtually any combination thereof, and that designingthe circuitry and/or writing the code for the software and or firmwarewould be well within the skill of one of skill in the art in light ofthis disclosure. In addition, those skilled in the art will appreciatethat the operations, functions, and data described herein are capable ofbeing distributed or stored in a variety of signal bearing media.Examples of a signal bearing medium include, but are not limited to,recordable type media such as floppy disks, hard disk drives, CD ROMs,digital tape, and computer memory, and transmission type media such asdigital and analog communication links using TDM or IP basedcommunication links (e.g., packet links). The choice of signal bearingmedium will generally be a design choice representing tradeoffs betweencost, efficiency, flexibility, and other implementation considerationsin a particular context, and none of these signal bearing media isinherently superior to the other.

Other embodiments of the invention will be apparent to those skilled inthe art from a consideration of the specification or practice of theinvention disclosed herein. It is intended that the specification beconsidered as exemplary only, with the true scope and spirit of theinvention being indicated by the following claims.

1. A lithographic method, comprising: positioning a mask proximate to asubstrate; and shifting the relative position of the mask and thesubstrate by actuating an electroactive polymer member.
 2. The method ofclaim 1, further comprising monitoring distances between the mask andthe substrate at a plurality of locations, wherein the electroactivepolymer member comprises a plurality of separably actuatable activeregions, and wherein actuating the electroactive polymer membercomprises separately actuating a subset of the separably actuatableactive regions in response to the monitored distances.
 3. The method ofclaim 1, further comprising maintaining a selected distance between themask and the substrate by using a monitored distance as a feedbacksignal to adjust a degree of actuation of the electroactive polymermember.
 4. The method of claim 1, wherein shifting the relative positionof the mask and the substrate comprises bringing the mask and thesubstrate into contact.
 5. The method of claim 4, further comprisingusing a monitored contact force as a feedback signal to adjust a degreeof actuation of the electroactive polymer member.
 6. The method of claim4, further comprising monitoring contact forces at a plurality oflocations between the mask and the substrate, wherein the electroactivepolymer member comprises a plurality of separably actuatable activeregions, and wherein actuating the electroactive polymer membercomprises separately actuating a subset of the separably actuatableactive regions in response to the monitored contact forces.
 7. Themethod of claim 1, wherein the electroactive polymer member comprises aplurality of separably actuatable active regions.
 8. The method of claim1, wherein the change of position or shape of the electroactive polymermember flattens the substrate.
 9. The method of claim 8, furthercomprising measuring flatness of the substrate, wherein theelectroactive polymer member comprises a plurality of separablyactuatable active regions, and wherein actuating the electroactivepolymer member comprises separately actuating a subset of the separablyactuatable active regions in response to the measured flatness of thesubstrate.
 10. The method of claim 1, wherein the change of position orshape of the electroactive polymer member flattens the mask.
 11. Themethod of claim 10, further comprising measuring flatness of the mask,wherein the electroactive polymer member comprises a plurality ofseparably actuatable active regions, and wherein actuating theelectroactive polymer member comprises separately actuating a subset ofthe separably actuatable active regions in response to the measuredflatness of the mask.
 12. The method of claim 1, further comprisingexposing the substrate to an energy flux through the mask.
 13. Themethod of claim 12, wherein the substrate is coated with a resistcomposition, and wherein the energy flux causes a chemical change in theresist composition.
 14. The method of claim 1, further comprisingexposing the substrate to an energy flux from the mask.
 15. The methodof claim 14, wherein exposing the substrate to the energy flux from themask comprises applying a voltage to the mask.
 16. The method of claim14, wherein exposing the substrate to the energy flux from the maskcomprises causing the mask to emit light.
 17. The method of claim 1,further comprising causing a physical effect on a surface of thesubstrate by contact with the mask.
 18. The method of claim 17, whereinchemical composition of the surface is changed by contact with the mask.19. A method of positioning a mask, comprising: applying a force with anelectroactive polymer.
 20. The method of claim 19, wherein applying aforce comprises applying a force to a mask moving mechanism.
 21. Themethod of claim 19, wherein applying a force comprises deforming themask.
 22. A method of exposing a substrate, comprising: shifting therelative position of a mask and the substrate by actuating anelectroactive polymer member; and exposing the substrate to an energyflux through the mask.
 23. A method of exposing a substrate, comprising:shifting the relative position of a mask and the substrate by actuatingan electroactive polymer member; and exposing the substrate to an energyflux from the mask.
 24. The method of claim 23, wherein exposing thesubstrate to an energy flux from the mask comprises applying a voltageto the mask.
 25. The method of claim 23, wherein exposing the substrateto an energy flux from the mask comprises inducing the mask to emitlight.